Objectives: Mental disorders are highly prevalent in eight South Asian countries, yet there is a gap of a synthesized overview of the prevalence of mental disorders in this region. This umbrella review aims to summarize the prevalence of mental disorders from systematic reviews and metaanalyses of South Asian studies. Materials and methods: A systematic search of 11 major databases and additional sources was conducted until December 11, 2019. Articles were included if they were systematic reviews or meta-analyses, reported the prevalence of mental disorders, and reported primary studies conducted in South Asian countries only. Results: Among 2591 citations, a total of 23 reviews met all the criteria of this umbrella review. The synthesized findings from those reviews suggest high prevalence rates for mental disorders, including depressive disorders, anxiety disorders, mood disorders, suicidal behavior and selfharm, schizophrenia, substance use disorders, neurodevelopmental disorders, dementia, and other mental health problems. Also, findings suggest a high burden of maternal depression, psychiatric comorbidities in chronic physical illnesses, and various mental disorders among children, elderly adults, refugees, and other vulnerable populations. Most studies were from India whereas evidence from Afghanistan, Bhutan, and Maldives was limited. Conclusion: The findings of this review are constrained with heterogeneity in prevalence estimations, methodologies, sampling issues, and limitations in the existing literature, which should be addressed in future research. The evidence synthesized in this review provides national and regional overview of the prevalence of mental disorders, which may inform better policymaking and practice advancing mental health in South Asia.